Can babies beat bullies? The New York Times has an in-depth look at the school-based Roots of Empathy antibullying program — TIME explored it earlier here and here — which works by introducing schoolchildren to a mother and baby. Kids bond with the baby over a series of visits, which has been shown to increase kindness and reduce bullying.

The fact that babies make people go mushy isn’t surprising. But how it works is still a bit of a mystery. Writes David Bornstein in the Times:

The baby seems to act like a heart-softening magnet. No one fully understands why. Kimberly Schonert-Reichl, an applied developmental psychologist who is a professor at the University of British Columbia, has evaluated Roots of Empathy in four studies. “Do kids become more empathic and understanding? Do they become less aggressive and kinder to each other? The answer is yes and yes,” she explained. “The question is why.”

C. Sue Carter, a neurobiologist based at the University of Illinois at Chicago, who has conducted pioneering research into the effects of oxytocin, a hormone that has been linked with caring and trusting behavior, suspects that biology is playing a role in the program’s impact. “This may be an oxytocin story,” Carter told me. “I believe that being around the baby is somehow putting the children in a biologically different place. We don’t know what that place is because we haven’t measured it. However, if it works here as it does in other animals, we would guess that exposure to an infant would create a physiological state in which the children would be more social.”

Oxytocin is a fascinating hormone. It appears to rewire the brain, helping to link feelings of pleasure and trust to certain people. Oxcytocin is what helps parents bond with their babies, for instance. So when a parent sees his or her child (or when a child sees his or her parent), brain regions involved in stress relief and pleasure release neurotransmitters like dopamine and endogenous opioids in patterns that produce a sense of safety and contentment. Mom, Dad and Baby’s brains are essentially “addicted” to each other. Indeed, in animal studies, when babies are separated from their mothers, opioid drugs like morphine and heroin are some of the only things that stop their separation cries. (More on TIME.com:How the ‘Mommy Brain’ Grows and Why There’s No Such Thing as Too Much Love)

Oxytocin isn’t like heroin, though. On its own, it doesn’t actually produce a “high” — which is why it isn’t a controlled substance. But what it does do is help us connect people with pleasure and hold relationships together. In the Roots of Empathy program, the mother and baby don’t visit the classroom once — they do so repeatedly so that the children develop an ongoing relationship with them. And when the kids’ joys are linked to those of someone else, compassion is natural.